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Biomedical subjects

W W Li

Publications and source records attributed to W W Li.

At least 91 records · Page 5Linked to original sources
PubMed1989

Effects of lectins with various carbohydrate binding specificities on lipid metabolism in isolated rat and hamster adipocytes.

1. Mannose-binding and N-acetylglucosamine binding lectins exhibited potent antilipolytic and lipogenic activities. 2. Fucose-binding lectins had minimal lipogenic activity but possessed antilipolytic activity. 3. Most galactose-binding and N-acetylgalactosamine-binding lectins were devoid of significant antilipolytic and lipogenic activities. Notable exceptions were lectins from Momordica charantia, Wisteria floribunda, Vicia villosa, Codium fragile and the Siberian pine tree. lipogenic activity but lacked antilipolytic activity. 5. The galactose-binding horse gram and osage orange lectins exerted antilipolytic activity in hamster but not in rat adipocytes.

Acetylglucosamine↗
PubMed1989

The basis for intrinsic drug resistance or sensitivity to methotrexate.

Natural resistance to MTX in three different types of malignant cells is discussed. Two causes of resistance found were impaired drug uptake and impaired polyglutamylation. These resistance mechanisms have also been described to occur in cell lines with acquired resistance to this drug. In cells with acquired drug resistance, these phenotypic changes may reflect mutations in genes associated with transport of MTX or the enzyme DHFR, or in some circumstances reversion of the cell to a different phenotype without a mutational event. In cells with intrinsic resistance, the genetic mechanism responsible for these phenotypes is not known. Alternate treatment programs, e.g., with TMTX, or with TMTX and CPG2, a folate depleting enzyme, are under evaluation for these MTX resistant neoplasms.

Carcinoma, Squamous Cell↗
PubMed1989

Optic nerve sectioning does not affect the development of the retina.

The development of the retina of the albino rat was studied after sectioning of the optic nerves on the 2nd postnatal day. The 2nd day represents a stage at which the retina shows only the ganglion cell layer clearly delineated from an undifferentiated mass. Section of optic nerves at this stage did not affect the subsequent retinal development. Both control and experimental eyes developed at the same pace. Some minor degrees of 'retardation' e.g. the sizes of outer segments, appeared to deviate in the experimental retinae.

Animals↗
PubMed1989

[Detection of sickle cell gene by analysis of amplified DNA sequences].

This paper describes a technique of DNA amplification in vitro and its application on detection of sickle cell (Hb S) gene. Genomic DNA was microextracted from dried blood specimen of the first patient with sickle cell trait in China. Target DNA sequence was amplified by the polymerase chain reaction (PCR) with the primers beta 1 (5'-ACACAACTGTGTTCACTAGC-3') and beta 2 (5'-CAACTTCATCCACGTTCACC-3') that primed amplification of an 110-base-pair (bp) segment of beta globin gene. The amplified DNA was digested with a restriction endonuclease Mst II, which has a recognition site at codon 6 in the normal beta globin gene, and cleaved the normal amplified beta globin DNA into two fragments of 54bp and 56 bp which was as an overlap band in agarose gel electrophoresis, while the 110bp fragment amplified from DNA of sickle cell mutation remained uncleaved owing to a single base substitution (A----T) at codon 6 in the mutation. DNA amplification method is rapid, sensitive and simple, and does not require radioactive probes. Besides, the PCR amplification can be carried out on the DNA extracted from dried blood samples. So the technique is very useful for gene diagnosis and carrier screening of genetic disease.

Aged↗
PubMed1989

Stimulation of collagen formation in the intestinal anastomosis by low dose He-Ne laser.

The effect of low dose He-Ne laser on the healing of intestinal anastomosis was studied in the albino rat. A small piece of jejunum was removed from each rat and the ends sutured back with a simple interrupted pattern. In the experimental animal, the anastomosis was irradiated through an optic fiber with a He-Ne laser (1 mW) for 15 minutes whereas in the control animal, the anastomosis was not irradiated. The differences between the two groups were compared by histology, transmission electron microscopy, scanning electron microscopy and autoradiography 3 and 7 days after operation. The laser treated experimental animals demonstrated thicker collagen fibers and an increased quantity of collagen at the junction of the anastomosis compared to control animals. Increased uptake of labelled proline was also evident in the laser treated animals. These observations all point to a possible enhancement of collagen synthesis triggered by laser irradiation.

Anastomosis, Surgical↗
PubMed1989

Histochemical responses in the retina after acute blood loss.

Adult albino mice were bleed through the hearts by cardiac puncture under Nembutal anesthetic. 0.3 ml of blood was withdrawn form every animal. The retinae were then studied on a timed basis with succinic dehydrogenase histochemistry and alkaline phosphatase histochemistry. In control retinae, high SDH activities were localized in the inner segments, outer plexiform, inner plexiform, and ganglion cells layers and high alkaline phosphatase activities were localized in the ganglion cell layers and the vessels of the plexiform layers. Decrease in the enzymatic activities of both SDH and alkaline phosphatase in these layers were most evident 5h after bleeding. 9 to 24 h after bleeding, a compensatory increase was detected. 48 to 72 h after, the enzymatic activities decreased again. Reperfusion of experimental animals with 5% dextrose would increase the retinal enzymatic activities back to normal, even if the reperfusion was carried out as late as 48 h after bleeding.

Alkaline Phosphatase↗
PubMed1988

Trichosanthin, alpha-momorcharin and beta-momorcharin: identity of abortifacient and ribosome-inactivating proteins.

The abortifacient proteins trichosanthin, alpha-momorcharin and beta-momorcharin at nM concentrations inhibit cell-free protein synthesis. The momorcharins and the ribosome-inactivating proteins isolated from Momordica charantia seeds cross-react with the respective antisera. The ribosome-inactivating proteins saporins, pokeweed antiviral protein (PAP) and, to a lesser extent, gelonin have abortifacient activity on pregnant mice.

Abortifacient Agents↗
PubMed1988

Responses of the retinal pigment epithelium of the mouse after acute loss of blood.

Albino mice were bled through the hearts by cardiac puncture and 1/2, 1/3 and 1/4 mls of blood were taken out from 3 groups of animals. respectively. Half of the experimental animals were reinfused with 5% dextrose 1 h after bleeding. All were killed either 2, 5, 9, 24, 48 or 72 h after bleeding, and the phagosome numbers per 5 pigment cells counted and compared with control retinae. A severe decrease was evident after bleeding and the decrease leveled off 48 h afterwards. Reinfusion with dextrose had a positive beneficial effect.

Animals↗
PubMed1988

Morphological studies of the choriocapillaries and pigment epithelium of the eye after acute blood loss.

Albino mice were bled through the hearts and 1/3 ml of blood withdrawn from each animal. The choriocapillaries and the pigment epithelia of the eyes were selected for observations using the electron microscope. Morphological changes were apparent during the first 72 h after bleeding. Increase of vesicles in both the endothelial cells and the basal infoldings of pigment cells were features. Thickening of basal infoldings, thinning out of Bruch's membrane (with decrease content of fibrillary substances) as well as a transient disappearance of the diaphragms of pores of endothelial cells were also observed. Trypan blue dye was also found to have diffused into the retina in the first 24 h after bleeding. These processes appeared to augment the decreased nutrient supply to the retina after blood loss.

Animals↗
PubMed1987

Peptides with antilipolytic and lipogenic activities from seeds of the bitter gourd Momordica charantia (family Cucurbitaceae).

Decorticated Momordica charantia seeds were extracted with acidic ethanol. The pH of the extract was adjusted to 8 and the resulting precipitate was chromatographed on CM Sepharose CL-6B and then desalted on Sephadex G-10. A number of factors which exhibited antilipolytic and lipogenic activities in rat adipocytes were isolated. Two of the factors were demonstrated to be peptides with similar amino acid compositions and a molecular weight of approximately 8000. However the peptides greatly differed in their chromatographic behavior on CM-Sepharose CL-6B and in their mobilities in agarose and polyacrylamide gel electrophoresis.

Abortifacient Agents, Nonsteroidal↗
PubMed1987

Optic nerve transection and tectal removal affect phagocytic activity of the pigment epithelium in goldfish.

The phagocytic ability of the pigment epithelium after optic nerve sectioning and tectal removal was investigated in the goldfish by the method of ingestion of latex beads. 4 days after sectioning, an increase in latex beads was evident which decreased by the end of the first week. Tectal removal also triggered increase intake of latex beads which was presented after 7 days.

Animals↗
PubMed1987

Beta-trichosanthin: a new abortifacient protein from the Chinese drug, wangua, Trichosanthes cucumeroides.

beta-Trichosanthin was a new abortifacient protein purified from the Chinese drug, Wangua, root tubers of Trichosanthes cucumeroides (Cucurbitaceae). The purification procedure involved acetone fractionation, ammonium sulfate precipitation, ion-exchange chromatography on CM-Sepharose and preparative agarose electrophoresis. Homogeneity of beta-trichosanthin was demonstrated in immunoelectrophoresis, agarose electrophoresis and SDS-polyacrylamide gel electrophoresis. It had a molecular weight of 28,000 and no cysteine in its molecule. It differed from trichosanthin, a known abortifacient protein isolated from a related Chinese drug, Tianhuafen, root tubers of Trichosanthes kirilowii (Cucurbitaceae), in molecular weight, carbohydrate content, charge and amino acid composition. beta-Trichosanthin was, however, immunochemically identical to trichosanthin and was about twice as potent as trichosanthin in inducing mid-term abortion in mice.

Abortifacient Agents↗
PubMed1987

Isolation and characterization of an abortifacient protein, momorcochin, from root tubers of Momordica cochinchinensis (family cucurbitaceae).

A glycoprotein with a molecular weight of 32,000 as estimated by SDS-polyacrylamide gel electrophoresis, and characterized by an abundance of Asp and Glu residues and an absence of Cys residues in its amino acid analysis, was isolated from fresh root tubers of Momordica cochinchinensis using a procedure that involved acetone precipitation, ammonium sulfate precipitation, ion exchange chromatography on DEAE Sepharose CL-6B and gel filtration on Sephadex G-75. The protein was capable of inducing mid-term abortion in mice. The characteristics of this protein were compared and contrasted with those of the abortifacient proteins isolated from other plants of the Cucurbitaceae family.

Abortifacient Agents↗
PubMed1987

Acid-ethanol extractable compounds from fruits and seeds of the bitter gourd Momordica charantia: effects on lipid metabolism in isolated rat adipocytes.

Fruits and seeds of the bitter gourd Momordica charantia (Family Cucurbitaceae) were extracted with acidic ethanol. The extract was adjusted to pH 3 and proteins and peptides were precipitated by addition of a copious volume of acetone. The precipitate was dissolved, dialyzed and lyophilized. The resulting material, designated "p-fraction" was tested for antilipolytic and lipogenic activities. Seed "p-fraction" was further chromatographed on fetuin agarose to yield an unadsorbed fraction (F) which could be fractionated by gel filtration on Sephadex G-10 to give an unretarded fraction (F1) and a retarded fraction (F2). Fruit "p-fraction" exhibited antilipolytic activity in hamster adipocytes and stimulated 3H-glucose incorporation into lipids. F1, a saponin containing fraction, inhibited both lipolysis and 3H-glucose incorporation into lipids. F2 enhanced 3H-glucose incorporation into lipid. The results are indicative of the presence of compounds with insulinomimetic activities in M. charantia fruits and seeds.

Animals↗
PubMed1987

Isolation and characterization of an immunosuppressive protein from Trichosanthes kirilowii root tubers.

An immunosuppressive protein was isolated from Trichosanthes kirilowii root tubers by a procedure involving acetone fractionation and ion exchange chromatography on CM-Sepharose. Homogeneity of the protein was demonstrated in immunoelectrophoresis, SDS-polyacrylamide gel electrophoresis, gel filtration, high performance liquid chromatography and a single NH2-terminal sequence. The protein had a molecular weight of 26,000, aspartic acid as the NH2-terminal amino acid and no cysteine or carbohydrates in its molecule. It inhibited ConA-induced transformation in lymphocytes isolated from spleens of CBA mice. The protein was also potent in inducing mid-term abortion in mice.

Abortifacient Agents↗
PubMed1987

The eyes and the orbits of 2 species of fishes with "dorsal eyes".

The eyes of 2 species of fishes with dorsal eyes Uranoscopus oligolepis and Paralichthyes olivaceus were studied. In the Uranoscopus, ciliary projections were not conspicuous and in the Paralichthyes, the projections were small. 3 types of photoreceptors were observed in both species--rods, single cones and twin cones. In both species, the number of twin cones increased towards the central retinae and in the Paralichthyes, the single cones also increased in number. The rods were lowest in the central region. In the orbit, both species displayed complex solid bones. For example, the lateral border of the orbit was a complex formed by the lacrimal, suborbital, postorbital and parietal. In the Paralichthyes, the lateral orbital border was actually continuous with the orbital and parietal bones and the border was not distinct. The formation of fused plates would serve to restrict eye movement as well as to resist deep sea pressure acting from above.

Animals↗